The present invention relates to an apparatus for extruding bakery paste, such as bread dough, leavened dough, dough for pizzas, croissants and the like, flaky pastry such as biscuits and the like, and non-bakery pastes such as pasta for lasagna, ravioli, both with and without eggs.
Extrusion apparatuses are generally meant to produce a rather thin sheet without however stretching it or compressing it excessively, in other words without subjecting it to an "ill-treatment" which generally leads to one or more of the following problems: breakage of the fibers of the mix, and thus reduction in the elasticity of the paste, damage to the gluten, and alteration in the organoleptic qualities; this entails that it is impossible to obtain a finished product that resembles as closely as possible the result of a manual process in which the duration of the fragrance of the product in the course of time is enhanced.
So far, extruders have already been proposed that are formed by a hopper with a series of pairs of cylindrical lamination rollers arranged below the hopper. In this solution, the lamination rollers compress and stress the pasty mass in forming the continuous sheet of paste until they damage its fibers.
For example, from the United Kingdom Patent Specification No. 254,172 there is known a machine for rolling and folding or doubling dough which includes a hopper for containing a batch of dough mixture at the bottom of which there is provided an outlet for the dough mixture, and below which there is arranged a succession of cylindrical roller pairs through which the rough mixture of the ingredients of the dough mixture is successively rolled. The circumferential speeds of the roller pairs decrease in the direction of travel of the dough, and the gaps between the rollers of the successive pairs of rollers gradually increase in the same direction, such that the quick supply of a thin sheet of dough to a pair of rollers having a lower circumferential speed necessarily causes the dough sheet to be doubled or folded. The doubling and folding of the dough and successive feeding between the roller pairs generally compresses and stresses the pasty mass in forming the continuous sheet of paste until its fibers are damaged.
This ill-treatment of the dough mixture is further exacerbated by the provision of rotating shafts provided with short radially extending pins inside the hopper for stirring and distributing the dough in the hopper and forcing it to the hopper outlet at which the first upper pair of cylindrical rollers is directly arranged, such that the first upper pair of rollers is aided by the rotating shafts in gripping the dough.
Dough shaping apparatuses are known from United Kingdom Patent Specification No. 1,115,859 and published French Patent Application No. 2,559,029, which include rotating cylinders having radially protruding blades for pushing the dough to a shaping device disposed underneath the cylinders. The arrangement in these devices however is such as to create closed compression chambers between the cylinders and the shaping device which may lead to the excessive damaging of the dough.
There is also known from the U.S. Pat. No. 4,057,377 a vertical type noodle rolling apparatus wherein the noodle strip is progressively rolled as it is moved downwardly from a feed hopper and between a series of pairs of cylindrical rollers. The apparatus is suitable for forming noodle sheets, however the progressive compressing provided by the cylindrical roller pairs makes this type of apparatus generally unsuitable for forming sheets of paste for example in the form of leavened dough or other delicate dough wherein the progressive compression would lead to the damaging of the paste fibers and/or alteration of the qualities of the paste which are necessary such that the finished product resembles as closely as possible the result of a manual process.